Field of the Disclosure
The present disclosure, for example, relates to wireless communication systems, and more particularly to reporting channel feedback for non-orthogonal channels.
Description of Related Art
Wireless communication systems are widely deployed to provide various types of communication content such as voice, video, packet data, messaging, broadcast, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., time, frequency, and power). Examples of such multiple-access systems include code-division multiple access (CDMA) systems, time-division multiple access (TDMA) systems, frequency-division multiple access (FDMA) systems, and orthogonal frequency-division multiple access (OFDMA) systems.
By way of example, a wireless multiple-access communication system may include a number of base stations, each simultaneously supporting communication for multiple communication devices, otherwise known as user equipments (UEs). A base station may communicate with UEs on downlink channels (e.g., for transmissions from a base station to a UE) and uplink channels (e.g., for transmissions from a UE to a base station).
Communications systems may take advantage of multiple antenna techniques for increased reliability or capacity. Multiple antenna techniques include transmit diversity and multiple-input multiple-output (MIMO) techniques. MIMO systems that employ T transmit antennas and R receive antennas may realize a capacity increase of min {T, R} over single antenna techniques. Another approach includes the transmission of non-orthogonal downlink signals to increase the capacity of a wireless communication system. However, in a multiple access system, the possible variations in techniques including single-user MIMO (SU-MIMO), multiple-user MIMO (MU-MIMO), and/or non-orthogonal multiple access (NOMA) results in challenges in reporting channel conditions over the space of possible combinations of transmissions to multiple UEs.